A reporting application can modify a report design before generating the report. For example, the application can add or remove items from the report design based on the user who generates the report. To provide further customization of a report, during the generation of the output, a report design can use JavaScript classes or embedded JavaScript code to handle events. The classes in the Design Engine API support making changes to a report design and including or changing scripts. The key Design Engine classes are in the org.eclipse.birt.model.api package.

A deployed application must be able to access all the classes required for BIRT, the external data sources, and any other necessary classes. Check your web application server documentation to ensure required libraries and data sources are accessible to each application. In other environments, remember to set the CLASSPATH for your application and, for OSGi, set up the BIRT home directory in the BIRT_HOME environment variable.